// GPG4Browsers - An OpenPGP implementation in javascript
// Copyright (C) 2011 Recurity Labs GmbH
// 
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
// 
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// Lesser General Public License for more details.
// 
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

/**
 * @class
 * @classdesc Implementation of the strange "Marker packet" (Tag 10)
 * 
 * RFC4880 5.8: An experimental version of PGP used this packet as the Literal
 * packet, but no released version of PGP generated Literal packets with this
 * tag. With PGP 5.x, this packet has been reassigned and is reserved for use as
 * the Marker packet.
 * 
 * Such a packet MUST be ignored when received.
 */
function openpgp_packet_marker() {
	this.tagType = 10;
	/**
	 * Parsing function for a literal data packet (tag 10).
	 * 
	 * @param {String} input Payload of a tag 10 packet
	 * @param {Integer} position
	 *            Position to start reading from the input string
	 * @param {Integer} len
	 *            Length of the packet or the remaining length of
	 *            input at position
	 * @return {openpgp_packet_encrypteddata} Object representation
	 */
	function read_packet(input, position, len) {
		this.packetLength = 3;
		if (input.charCodeAt(position) == 0x50 && // P
				input.charCodeAt(position + 1) == 0x47 && // G
				input.charCodeAt(position + 2) == 0x50) // P
			return this;
		// marker packet does not contain "PGP"
		return null;
	}

	/**
	 * Generates Debug output
	 * 
	 * @return {String} String which gives some information about the 
	 * keymaterial
	 */
	function toString() {
		return "5.8.  Marker Packet (Obsolete Literal Packet) (Tag 10)\n"
				+ "     packet reads: \"PGP\"\n";
	}

	this.read_packet = read_packet;
	this.toString = toString;
}